Tube for boilers, heat exchangers, and the like



Aug. 9, 1932. R. s. BROWN 1,870,669

TUBE FOR BOILERS, HEAT EXCHANGERS, AND THE-LIKE Filed Jan. 2l. 1929 Patented Aug. 9, 1932 PATENT OFFICE ROGER STUART BROWN, F CHICAGO, ILLINOIS TUBE FOB BOILERS, HEAT EXCHANGEBSfAND THE LIKE Application led January 21, 1929.

'l` his invention relates to improvements in tubes used in boilers, superheaters or other heat exchangers for heating or ycooling various liquids, gases or solid media. It Willl be realized that I do not yvish to limit my-l self, except so far as set out specically in the claims, to any particular use of my invention, it being adaptable to a Wide variety of uses. However, I have herein illustrated it chiefly in connection With boiler tubes, which disclosure will be at least illustrative of the applications to Which the invention may be put. A

One object of the invention is to obtain a greater heat transfer per square foot of tube surface, thereby obtaining a greater capacity from apparatus of a given size or area of tube surface. Another object is to lessen or minimize draft resistance, for example by stream lining the exterior of the tubes, or by eliminating tortuosities of the passage or path traveled by the fluid. For example by stream lining the exterior of tubes at a given velocity of the medium, for instance furnace gases, such medium is circulated across a bank of tubes at more uniform speed and with less sharp turns.

A further object attained in some applications of my invention is the maintenance of a considerable reservoir of heat, as by the employment of large amounts of metal which may be held at relatively high temperatures, thus enabling a boiler-beer to meet fluctuating demands upon it. Y

Various other objects of my invention Will appear from time to time in the course of the specification and claims.

I illustrate my invention more or less diagrammatically in the accompanying drawing, wherein- Figure 1 is a transverse section through a bank of tubes.

Figure 2 is a side elevation of one of the tubes, with parts in longitudinal section; and

Figure vr-isfa section on the line 3-3 of Figure 2.

Like partsI are indicated by like symbols throughout the specification and drawing.

Referring generally to the drawing, I 1llustrate a bank of tubes, for example tubes Serial N0. 333,890.

for a boiler, which are staggered across the path of movement of the hot gases, and which are stream lined in section, the stream lining and the staggering being so arranged as to provide passages of generally constant crosssectional area, with the turns limited to a n nnlmum and with an elimination' of projections and bends, which tend to delay the circulation of the medium or to cause eddies or disturbances in the movement of the medium. The staggering of tubes across the path of flow of the heating medium increases the resistance to the flow, but such staggering is in many cases helpful or essential. It is to minimlze the unfortunate results of such staggering that I have developed the stream lining and uniformity of cross-section in passages above referred to.

For purposes of illustration I am describl ing the invention as applied to a water tube boiler with the Water inside the tubes and the product of combustion from the furnace circulating around and between the tubes. It will be understood that my invention may be employed regardless of what medium is inside and what outside the tubes, and regardless of which medium is the hotter.

Referring, for example, to Fig. 1, I illustrate tubes A A, each such tube having at diametrically opposed points a member or projection A1, which is stream lined, as shown in the figure.

Each such tube A is provided with an inner cylindrical tube A2, the inner tube being cylindrical or circular in cross-section, its cylindrical exterior conforming to the cylindrical interior of the tube A. The stream lining member or projection A1 is connected by a plurality of transverse webs or fins A3. Preferably these fins lie in parallel planes. As a matter of convenience they may liebin planes perpendicular to the axis of each 'tu e.

As a convenient means for attaching individual tubes to a header H, I may aperture the header as at H1, the aperture being of greater diameter than the maximum diameter of the tube. This aperture may be channeled asat l-I2 to permit a securing member H3 to be forced or expanded thereinto as at H4. The

lip oi 'the member H3 may be expanded as at F5, to lock against the exterior of the header lil. The inner cylindrical tube A2 may be eX- tended outwardly beyond the end of the stream-lined outer tube A, as shown in Figure 2, and it may be expanded, as shown at A", to Aila-r channel" i in the central aperture r' do ot wish 'to be limited to r securtie tubes to in s herein sh device, and have mu. icaticns and app do not wish to be Aitcd specifi a. orn'is herein describefl nd shown, except so far as l limit mysellthe language or i d claims. l wish my description and drawing to be taken as in a broad sense illustrative and diagrammatic, rather than as limiting ie precisely to the d-tails indicated.

The use and operation of my invention are as fellows:

ln current practice it is customary to stagger tubes across the path of movement of a fluid. My invention, when applied `for example to water tube boilers, has for its purpose to minimize the interference to the flow of the heated gases between and past the tubes and to increase the heat-absorptive surface. One phase oi" my invention is the provision of means or surfaces for confining the gases, as 'they pass between the tubes, to passages of relatively constant cross-sectional area. l?! here the tubes are staggered to obtain this result, as shown in Figs. l and following, by stream lining the tubes in cross-section and by arranging tubes, so stream lined, in such fashion that the distance between opposed tubes is constant, the result is an easy passage for the gases along a series or successions of flowing curves without sharpened points or angles or restrictions in the passage or expansion chambers, or any means orA ymethod likely to delay the flow of the heated medium. Y

I may form an individual pipe in any suitable manner but find it preferable to employ the usual pipe of cylindrical cross-section, and to cast or draw or shrink or otherwise position about it whatever exterior surface or heat absorbing member or jacket is desired. I indicate a stream-line form of exterior jacket but wish it realized that the particular proportions and shape may be widely varied in practice and my disclosure of this particular form or contour of pipe is primarily illustrative, although it is a practical form of jacket.

Stated generally, by the various forms of tube I illustrate, I obtain a uniform channel for the heated gases, a relatively smooth passageway of constant cross-section between tubes or between columns of tubes. l thereby obtain a minimum interfere-nce with the flow of the gases and a minimum loss of velocity as the gases pass each row or tubes.

At speeds below 3 feet a second stratiiied i'iow results, and it may be necessary to stir up the flow. But at speeds greater than this, there is constant turbulence oi" flow Within the medium, and no necessity of agitating the stream, which provides its own turbulence. lin commercial practice, boilers, heat changers, and the iii-Ie, develop velocities above the critical velocity where turbulence begins. instead of stirring up 'the now as by the employment of and tno like, it is my idea to disturb little as possible, to maintain a path of constant cross-section and to maintain Increment through series oie easy curves, where curves are employed, with a minimum change of velocity or direction any given point.

lit will be unc erstood that in using the term stream-lined l wish the term to be understood as broadly interpreted and including 'cr example devices having the diametrically opposed projecting stream-line hns or niembers shown herein. '.lhe term may also include the employment of but a single projection, orany formation of the exterior of a tube whereby the passage of a fluid thereabout, without eddy currents or interference or turbulence is substantially promoted. "Preferably l employ a device which is symmetrical in cross-section.

lt will be understood that in the manufacture of the tubes the outer streamlined acket A may be formed in sections of any suitable or convenient length, the final tube including the inner tubular member A2 with as many sections of the member A positioned therealong and thereabout as is necessary.

l claim:

l. A tube adaptable for use with heat exchangers and the like, the interior surface o' which is cylindrical in cross-section, the eX- terior surface of which is stream-lined in transverse cross-section, such stream-lining exterior being formed separately from, and surrounding, the central cylindrical portion.Y

2. For use with heat exchangers and the like, an inner tube and an outer member having its exterior stream-lined, in transverse cross-section, such exterior including a plurality of ribs lying in planes generally perpendicular to the axis of the tube.

3. A tube adaptable for use with heat exchangers and the like, the exterior of which is stream-lined, when taken in transverse section, said tube being provided with a terminal portion of generally circular cross-section, the diameter of said terminal portion exceeding the maximum diameter of the stream-lined portions, said tube including a cylindrical inner tube portion.

4.. A tube adaptable for use with heat eX- changers and the like, the exterior of which "ma GU is stream-lined, when taken in transverse section, said tube being provided with a terminal portion of generally circular cross-section, such terminal portion being formed separately from the stream-lined portion of the l tube and being secured thereto.

5. A tube adaptable for use with heat exchangers and the like, the exterior of which is stream-lined, when taken in transverse section, said tube being provided with a terminal portion of generally circular cross-section, such terminal portion being formed separately from the stream-lined portion and including a portion at one end, adapted to be connected to a header, and a portion at the other end adapted to receive the end of the streamlined lportion of the tube.

6. tube adaptable for use with heat exchangers and the like, the exterior of which is stream-lined, when taken in transverse section, said tube being provided with a terminal portion of generally circular cross-section, such terminal portion being formed separately from the stream-lined portion and including a relatively thin portion at one end, adapted to be connected to a header, and a relatively thick portion at the other end adapted to receive the end of the stream-lined portion ofD the tube, such 'stream-lined portion of the tube terminating in a portion adapted to penetrate the aperture of the terminal portion.

7 For use with heat exchangers and the like, a plurality of tubes arranged in staggered relation, the exteriors of said tubes being stream-lined in transverse cross-section, said tubes being arranged to provide passages therebetween of substantially uniform crosssectional area, each such tube including noncylindrical exterior stream-line means, and an interior cylindrical tube portion associated therewith.

8. For use with heat exchangers and the like, a plurality of tubes in aligned arrangement, the exterior walls ofsaid tubes defining passages, the distance separating the opposite walls of such passages being generally uniorm each such tube including a non-cylindrical exterior cover member and a cylindrical inner tube portion.

9. For use with heat exchangers and the like, a tube having an inner portion of generally cylindrical cross-section and an exterior portion of non-cylindrical cross-section, such exterior non-cylindrical portion including a plurality of exterior ribs lyingv in planes generally transverse to the axis of the tube.

10. For use with heat exchangers and the like, a tube having its exterior stream-lined in transverse cross-section, such exterior including a plurality of parallel ribs lying in planes generally transverse to the axis of the tube, said tube including a cylindrical inner tube.

11. For use with heat exchangers and the' like, an inner tube, an outer tube portion surrounding saidinner tube, said outer tube portion including diametrically opposed streamline projections, and a plurality of ribs con-` 1 bounded by smooth Howing curves, said tubes including cylindrical inner tube members.

14. For use with heat exchangers and the like, a plurality of tubes arranged in staggered relation, the exterior walls of which, when taken in transverse section, are bounded by reverse curves, the passages between adjacent tubes, bounded by said curves, being of substantially uniform width between opposed surfaces of adjacent tubes, said tubes including interior cylindrical tube members.

15. A lgube adaptable for use with heat exchangers and the like, the exterior of which, when taken in transverse section, is bounded lby smooth flowing reverse curves said tube including a central cylindrical tu e.

16. For use with heat exchangers and the like, an inner tube and an outer member having its exterior stream-lined in transverse cross-section, such exterior including a plurality of ribs, adjacent ribs lying in generally parallel planes.

17. A tube adaptable for use with heat exchangers and the like, t-he exterior of which is stream-lined, when taken in transverse section, said tube being provided with a terminal portion of generally circular cross-section, the diameter of said terminal portion exceeding the maximum diameter of the stream-lined portion.

18. A tube adaptable for use with heat exchangers and the like, the exterior of which is stream-lined, when taken in transverse section, said tube being provided with a terminal portion of generally circular crosssection, such terminal portion being formed separately from the stream-line portion of the tube and being secured thereto, said tube including an inner tube member.

19. A tube adaptable for use with heat exchangers and the like, the exterior of which is stream-lined, when taken in transverse section, said tube being provided with a terminal portion of generally circular crosss'ection, such terminal portion being formed separately from the stream-lined portion and including a portion at one end, adapted to be connected to a header, and a portion at the other end adapted to receive the end of the stream-lined portion of the tube, said tube including an inner tube member.

20. A tube adaptable for use with heat exchangers and the like, the exterior of which 5 is stream-lined, when taken in transverse section, said tube being provided With a terminal portion of generally circular cross-section, such terminal portion being formed separately from the stream-lined portion and including a relatively thin portion at one end, adapted to be connected to a header, and a relatively thick portion at the other end adapted to receive the end of the stream-lined portion of the tube, such stream-lined portion of the tube terminating in a portion adapted to penetrate the aperture of the terminal porlt)ion, .said tube including an inner ltube mem- 2l. F or use With heat exchangers and the like, a plurality of tubes arranged in staggered relation, the exteriors of said tubes being stream-lined in transverse cross-section, said tubes being arranged to provide passages therebetween of substantially uniform crosssectional area, the Walls of the passages thus formed defining a succession of reversed curves, said tubes being provided With parallel ribs, portions of said tubes between said ribs defining passageways of substantially uniform cross-section- 22. A tube adaptable for use With heat exchangers and the like the exterior of which, when taken in transverse section, is streamlined, said tube including a cylindrical inner tube, said cylindrical inner tube portion eX- tending at the end of the tube longitudinally beyond the exterior streamlined portion.

Signed at Chicago, county of Cook and State of Illinois, this 18th day of January,

ROGER STUART BROWN. 

